Pilot signals—sometimes also referred to as reference signals—are typically used for determining the condition of a channel implemented on a radio link of a cellular network (channel sensing). Channel sensing may comprise channel estimation and channel measurements. In reference implementations, pilot signals are reoccurring communicated in order to consider time-dependencies of the channel condition, e.g., due to time-varying multipath effects or Doppler spread. The pilot signals are transmitted having well-defined transmit parameters such as amplitude and phase. From the received pilot signals and based on knowledge of the transmit parameters, it is then possible to deduce properties of the radio link between transmitter and receiver and conclude on a corresponding condition of the channel. Examples of uplink (UL) pilot signals are described for the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) radio access technology (RAT) in 3GPP Technical Specification (TS) 36.211 V.13.0.0 (2015-12) 5.5; examples of downlink (DL) pilot signals are described for the 3GPP LTE RAT in 3GPP TS 36.211 V.13.0.0 (2015-12) 6.10.
The amplitude with which pilot signals are transmitted defines a transmit power. Tailoring the transmit power can impose certain challenges. Typically, a tradeoff situation exists between increased interference (for large transmit powers) and inaccuracies of channel sensing (for small transmit power).